Levin A, Klassen J, Halperin M L
Renal Division, St. Paul's Hospital, University of British Columbia, Vancouver.
Clin Invest Med. 1995 Oct;18(5):401-5.
Polyuria is usually the result of a water diuresis or an osmotic diuresis. Traditionally, the assessment of the extracellular fluid (ECF) volume and the concentration of Na+ in plasma is sufficient to differentiate between the two. We present a case and our approach, which is based on calculations and quantitation of osmoles, to demonstrate the utility of this approach. A patient with diabetes mellitus, human T-cell lymphocyte virus, type 1 (HTLV-1) associated lymphoma, and hypercalcemia presented with marked ECF volume contraction and polyuria. A spot urine osmolality was 567 mOsm/kg H2O in the face of urine output of approximately 6 L/d. The initial diagnosis was an osmotic diuresis. However, a quantitative analysis revealed the enormous number of osmoles could not be accounted for physiologically. Hence, we postulated a water diuresis to be the cause of the polyuria. To confirm this hypothesis, we found that at different times during his hospitalization, the urine specific gravity ranged from 1.005 to 1.022, and urine output varied markedly over 8-h periods. Despite a plasma sodium of 147 mmol/L, the patient did not complain of thirst. Taken together, this suggested the presence of a hypothalamic lesion which caused central diabetes insipidus with variable output of antidiuretic hormone together with a blunted thirst response. Illustration of the utility of a quantitative approach to polyuria is the focus of the discussion.
多尿通常是水利尿或渗透性利尿的结果。传统上，评估细胞外液（ECF）容量和血浆中Na+浓度足以区分这两者。我们介绍一个病例以及我们基于渗透摩尔计算和定量的方法，以证明这种方法的实用性。一名患有糖尿病、1型人类T细胞淋巴细胞病毒（HTLV-1）相关淋巴瘤和高钙血症的患者出现明显的ECF容量收缩和多尿。在每日尿量约6 L的情况下，随机尿渗透压为567 mOsm/kg H2O。初步诊断为渗透性利尿。然而，定量分析显示大量的渗透摩尔无法从生理学角度解释。因此，我们推测多尿的原因是水利尿。为了证实这一假设，我们发现在其住院期间的不同时间，尿比重在1.005至1.022之间，并且尿量在8小时内有明显变化。尽管血浆钠浓度为147 mmol/L，但患者并未诉说口渴。综合来看，这提示存在下丘脑病变，导致中枢性尿崩症，抗利尿激素分泌可变，同时口渴反应迟钝。讨论的重点是多尿定量方法实用性的例证。
